The present invention relates to a method of and an apparatus for testing an alloy. More particularly this invention concerns a system for determining the composition of a metal alloy, by comparison with a given testpiece.
It is frequently necessary in the steel-making industry periodically to test the composition of the alloy being produced. In a rolling mill or the like it is also often required to verify the composition of the bars, blooms, or billets that are delivered, as an attempt to roll or draw the wrong type of steel can result in damage to the mill machinery.
The necessary quantitative and qualitative analysis is typically carried out in the plant laboratory. A unipolar spark is passed between an electrode and a sample of the workpiece. The light produced by this spark is reflected off a concave diffraction grating so as to produce a diffraction spectrum. The spectrum lines of interest, that is those representing for example iron, chrome, copper, molybdenum, or carbon, are converted into electronic signals having a signal level proportional to the respective line intensity. These various signals are then fed to a computer which can analyse them and print out the composition of the alloy.
Although such an arrangement is extremely accurate, producing an analysis that recites all of the important possible constituents of the alloy, it does not lend itselt to the continuous surveillance of alloy composition, which frequently can vary from charge to charge in a steel plant. Furthermore, the complexity of this analysis system makes it unsuitable in an automatic sorting operation, as the complex analysis takes considerable equipment and time. Thus the industrial solution has been to make periodic analyses of the product, balancing on the one hand the feasibility of the frequent stoppage for analyzing and on the other hand the necessity of controlling product quality.